Lifting-jack



(No Model.)

G. H. SHAFFBR '& J. BAIRSTOW. LIFTING JACK.

No. 404,800. Patented June 4, 1889.

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UNITED STATES PATENT OFFICE.

GEORGE H. SHAFFER AND JOHN BAIRSTOW, OF KENT, OHIO.

LlFTlNG-JAC K.

SPECIFICATION forming part of Letters Patent No. 404,800, dated June 4, 1889.

Application find January 14, 1889. Serial No. 296,454. (No model.)

5 Ohio, have jointly invented a new and useful Improvement in Lifting-Jacks, of which the following is a specification.

In the drawings forming a part hereof, Figure 1 is a side elevation of the lifting-jack Fig. 2 is an end elevation of the same. Figs. 3 andet represent detailed parts of the same on an enlarged scale.

The lifting-bar is operated by means of re- I 5 taining-cams c c and similar lifting-canls c c, lever 71, links f f, and releasing-lever i, the cams being connected with friction-blocks d d, and all supported by a suitable frame or casingg. The lifting-cams c c are identical in form with retaining-cams c c, the former having their trunnions b I) connected with links f f, and the latter having their trunnions b I) connected with the casing g. Friction-blocks (Z are formed at one end to receive the eccentric or cam c, and at the other end on the inner side thereof to engage with the lifting-bar a on the opposite side from the cam. Each cam c engages with the end of the friction-block of the other cam c 0 to press it against the lifting-bar a. Trunnions b b are loosely connected with links f f,

and bar a is lifted by pressing down the outer arm of lever h, which causes cams c c to press friction-blocks d cl against bar a.

Frame or easing g is formed with suitable bearings for bar a to slide in.

Blocks (Z d may, if desired, be loosely connected by one or more links 8', pivoted at each end to the blocks, as shown in Fig. 3, to

insure retaining them in position; but we do not consider such links essential.

Retaining-blocks d d by their own weight are brought in contact with bar a and hold it from falling while the outer arm of lever 5 h is being lifted to lower cams c c and blocks (1 d on bar a for the purpose of obtaining a new and lower grip on the baigwhen the outer arm of lever h is again pressed down.

To lower bar a, blocks d are lowered by lifting-lever it until the blocks are released from their hold on the bar by coming in contact with a projection s on the casing, which slightly raises them, or rather retains them, while the cams c are turned by the downward movement of links f to relieve the pressure on blocks (Z, and at the same time by pressing down lever 2', whose inner end is in contact with blocks (1, the latter are slightly raised to release them from bar a and allow the latter to descend. Bar a is formed with a projecting feet a for lifting railroad-tracks and other articles.

We claim as our invention 1. In a lifting-jack, a pair of lifting friction-blocks having bearings opposite each other and on opposite sides of the lifting-bar, in combination with said bar, a cam pivoted to each of said blocks and having a bearing against the other and having a trunnion or support connected with the casing of the lifting-jack, and retaining friction-blocks, substantially as described.

2. In a lifting-jack, a pair of lifting friction blocks and cams, the blocks having bearings on the lifting-bar opposite each other and the cams being pivoted to the blocks and each having a bearing against the end of the block of the other cam, substantially as described.

3. In a lifting-jack, the combination of a pair of lifting-cams and friction -blocks, connected by links, retaining-blocks, a lever to operate the retaining-blocks, and a lever and link to operate the friction-blocks, substantially as described.

4. In a lifting-jack, the combination of a pair of lifting friction-blocks having bearings on opposite sides of the lifting-bar, each of said blocks being provided with a cam supported in the frame of the lifting-jack and having bearing against the other block, retaining friction-blocks, a lever to operate the same, and a lever and links to operate the lifting friction block, substantially as described.

GEORGE H. SHAFFER. JOHN BAIRSTOW. itnesses:

BRADFORD IIOWLAND, GEO. F. ROBINSON. 

